Hydraulic setting tool with pressure multiplier

ABSTRACT

A hydraulically operated setting tool for use in setting a plug or other component in a wellbore, and which is responsive to a supply of input actuating pressure to actuate the tool. An elongate tool housing has an inlet to receive the supply of actuating pressure, and an actuator element is axially displaceable relative to housing and also engageable with the plug or other component to set and release the component with respect to the wellbore. A pressure multiplier arrangement includes a hydraulically operated low pressure and high volume output piston which performs initial loading of the tool, and a high pressure, low volume output piston which provides a multiplied hydraulic force applied to the actuator element to set the plug or other component in a required position in the wellbore.

[0001] This invention relates to a setting tool for use in a wellbore,and a method of setting a plug in a wellbore.

BACKGROUND TO THE INVENTION

[0002] In the petrochemical industries, there are many occasions whenrepair to a well is required or when flow should be closed off. This isaccomplished by use of a device called a plug. This device sealspressure from above and below and normally features a rubber or similarpacking element arranged around the outside of the plug, a “slip”mechanism to engage and lock the plug with the metal tubulars of thewellbore and a body to join the elements together. This plug becomes apressure barrier and allows work to be safely carried out above with nopossibility of well fluids escaping. Pressure retaining capability maybe as much as 10,000 psi and it may operate in temperatures of 300 degF. or higher.

[0003] Many types of plug exist available in a complete range of sizesand from a multitude of manufacturers. The plugs may be conveyed to therequired setting depth in the wellbore on pipe but more commonly on awireline. When positioned at the required depth, the plug must be set,normally requiring locating pins to be sheared with a moderate force,the slips to be energised, again with a moderate force and the rubberelement to be expanded again with moderate force. During this stage ofsetting, the forces required are only a few thousand pounds but thestroke may be quite long (7 inches or more). Finally, large forces of 20thousand pounds or more are required (over a short stroke of 1.0″ orless) to fully energise the rubber packing element, to force the slipsinto a biting engagement with the tubing wall and to disconnect thehydraulic power device from the plug.

[0004] The generic name for the running tool which provides the largesetting forces required is a “setting tool”. There are two industrystandard setting tools, namely the Baker E4 setting tool and theHalliburton (or GRC as formally known) “Shorty”. Both these toolsoperate using the same method. The method is to create and contain ahigh pressure gas by igniting a pyrotechnic charge in a closed chamber.The pyrotechnic or “black powder” charge is initiated by application ofan electrical current typically of around 20 volts. This is most usuallysupplied from surface down an electric wireline cable but may also besupplied from batteries used in conjunction with a pre-programmed clockor other memory device which switches the power to the charge. Thechamber which contains the high pressure gas features a floatinghydraulic piston with an oil filled chamber below splitting the chamberinto two sections. The hydraulic oil is pressured by the gas andprovides hydraulic power which when diverted to a secondary piston,performs the setting task as described previously. The power generatedby the setting tool is available over the entire stroke of the settingtool, the device automatically adjusting to different strokerequirements.

[0005] The setting tool is connected to the plug by a “shear stud”,normally a threaded rod with a waisted middle to provide a weak point.The shear stud may be rated to as much as 50,000 lbs. Use of the shearstud guarantees the required amount of force has been imparted to theplug below. Following setting, one half of the shear stud will bereturned with the setting tool, and the other will remain with the plug.

[0006] Following setting, the setting tool will retain the gas pressureuntil this is relieved. This normally entails opening a valve followingrecovery on surface. The high pressure gas is vented to atmosphere undercontrolled conditions. Not only is the handling of a highly pressurisedgas containing vessel dangerous, but the venting of the gas is ahazardous operation and must be conducted under strictly controlledconditions.

[0007] Many rules and regulations exist regarding the shipping andhandling of pyrotechnics as they are part of the family of explosives.Trained personnel are required at every stage and there are manylimitations on the use of pyrotechnics, especially regarding airfreight. Safety provisions must be made such as storage in licensedpremises and many third parties must be involved including notificationof the Harbour Master when shipping by sea, regular inspections both bythe Fire Brigade, local authority (for licensing requirements) and thePolice for security issues. The gas chambers of setting tools mustundergo regular N.D.T. inspections for cracks and other damage due totheir onerous use.

[0008] Obviously, as can be seen from the above, the use of pyrotechnicsis to be avoided if at all possible, but there are only limitedalternatives at present. One method is to use a “Hydrostatic SettingTool”. This type of tool converts the ambient hydrostatic pressure in awellbore into an hydraulic force to set the plug. The tool is equippedwith a series of pistons which each have atmospheric pressure on bothsides of the piston. They are modified pyrotechnic setting tools andretain the hydraulic lower section replacing the gas section with thepistons. When a valve is opened (either by a signal from surface or by atimer device) well pressure is allowed to act upon one side of thepistons causing an imbalance similar to the hydrostatic ambientpressure. As bottom hole well pressures are commonly in the range of2,000 to 8,000 psi, a straight 1 to 1 ratio will not produce sufficienthydraulic power to set a plug. The pistons must therefore incorporate apressure multiplier to generate the high pressures needed. Typically a 1to 5 multiplier may be required. This means therefore that for thevolume of hydraulic oil required for the stroke to set the tool, atleast 5 times that volume (or stroke) in the well pressure chamber mustbe present. A contingency of around 50% of the stroke is also requiredin order that the setting pistons do not bottom out without releasingthe shear stud and disconnecting from the plug. This tool is verycumbersome and unwieldy due to its extreme length and its performance isonly marginal in certain circumstances. Limited space is available tointroduce tools into a wellbore and extreme lengths preclude some toolsfrom operational use. Without increasing the pressure multiplier ratioto perhaps 10 to 1 and increasing the length accordingly, this devicehas very limited application and is seldom used.

[0009] It is an object of the invention, to provide a pressure activatedsetting tool which can offer all the benefits of a non pyrotechnicsetting tool but with the performance, output and short length of theexplosive type.

[0010] According to the invention there is provided a hydraulicallyoperated setting tool as defined in claim 1.

[0011] Preferred aspects of the invention are set out in dependentclaims 2 to 11.

[0012] As has been stated earlier, the output from a pyrotechnic settingtool is a high pressure gas charge with the high pressure available overthe entire stroke. This is due to the compressibility of gas, but isinefficient as around {fraction (4/5)} of the stroke is used to “take upthe slack” in the setting tool and the bridge plug. This includesshearing light retaining pins, expanding elastomers and strokingmandrels to close up gaps. Only a few thousand pounds force is requiredfor this.

[0013] Once all the slack has gone and the major movement has finished,high forces are required to energise the slips with the tubing wall,energise the packing element the final portion and to shear the releaseshear stud. The setting process requires two distinct hydraulicoperations, each with different properties. Firstly a long stroke lowpressure operation followed by a short stroke high pressure operation.

[0014] A Pressure Activated Setting Tool according to the invention isable to combine both these operations in one device and a preferredembodiment will now be described in some detail with reference to FIG. 1of the accompanying drawings.

[0015] Shown in FIG. 1a, to the left of the drawing, are the threeinitiating option modules, namely an adaptor 10 to electric wirelinecable, a memory clock type device 11 for slickline use, and a hydraulicconnector 12 for use in shallow setting depths. All three of theseoption modules allow well pressure (or hydraulic pressure supplied fromsurface in option 3) to selectively enter the tool at the top wheninitiation is required. The tool (designated generally by reference 14in FIG. 1b) is oil filled and features a rod type central piston (highpressure, low volume) which is detachably connected to an annular type(high volume, low pressure) piston. In the example shown, shear pins ofa specific pre determined value interconnect the pistons. A ratchetmechanism at the bottom of the annular piston completes the internaldetail of the tool.

[0016] In response to well pressure entering the top of the tool, (shownin FIG. 1b) the LP piston combined with the HP piston both displacehydraulic oil into an outer sleeve type piston forcing it downwards andcausing an attached plug to compress. The centre portion of the plug(not shown) is retained at this time by a shear stud 16 which is shownat the bottom of the illustration with the outer setting tool hydraulicsleeve pressing downwards. The L.P. section of the tool has a ratio of 1to 2, doubling the available well pressure until such time as allmovement has been accomplished with this pressure. The shear connectionlinking the LP and HP pistons will now shear allowing the HP piston toexert increased loads on the plug. The ratchet arrangement prevents thehydraulic pressure from returning the LP piston back to its startingpoint and isolates the LP piston from the system. The HP piston has aratio of 1 to 10 increasing well pressure 10 times. This will nowproduce the last part of the stroke required to fully set the plug andrelease the shear stud.

[0017] A plug adapter 15, shown in FIG. 1c carries the shear stud 16(which attaches the plug to the tool), and is secured to the lower endof the tool 14.

[0018] By use of this method, hydraulic forces well in excess of 50,000lbs are available to set a variety of plugs without use of pyrotechnics.The device will self compensate for different plug types and willautomatically change over from LP to HP operation once the required“slack” has been removed from the system.

[0019] The construction of the tool will now be described in detail,with reference to FIGS. 1a, b and c of the drawing.

[0020] The hydraulically operated setting tool is designated generallyby reference 14, and is intended to be used in setting a plug or othercomponent in a wellbore, and being responsive to a supply of inputactuating pressure to actuate the tool. Any suitable one of theconnector modules 10, 11 and 12, shown in FIG. 1a, may be used in orderto complete the assembly of the tool, ready to be raised and lowered toa required position along the length of the wellbore, via suitableflexible connection to the surface. The module 10 may be used to connectthe tool to an electric wireline, whereas the module 11 can be used toconnect the tool to a slickline. The module 12 may be used to provide anhydraulic connection to surface, in shallow drilling depths, when aremote input actuating pressure is used in order to actuate the tool.However, in the case of the modules 10 and 11, it will be wellboreambient pressure which will be used in order to actuate the tool.

[0021] The plug adapter 15 is detachably connected to a lower end of thetool 14, and carries shear stud 16 which is the means employed in orderto attach a plug (not shown), or other component which is to be set inposition in the wellbore.

[0022] The tool 14 has an external elongate housing designated generallyby reference 17, and which is movable lengthwise during lowering andraising of the tool 14 in the wellbore. Housing 17 has an inlet 18 toreceive the supply of actuating pressure which, as mentioned above, maybe wellbore pressure, or an external supply of actuating pressure fromthe surface.

[0023] An actuator element is axially displaceably mounted on thehousing 17, and the illustrated arrangement comprises an outer hydraulicsetting sleeve 19. Sleeve 19 is engageable with the plug or othercomponent, to set and release the component with respect to thewellbore, upon axial displacement of the sleeve 19.

[0024] A pressure multiplier arrangement is provided in the housing 17,and comprises a detachable connection together of a low pressure piston20 and a high pressure piston 21. In the illustrated example, adetachable connection between pistons 20 and 21 takes the form of shearpins 22. However, it should be understood that other means may beutilised in order to provide a detachable connection between pistons 20and 21, upon application of a predetermined load therebetween.

[0025] The void outside the low pressure and high pressure pistons isoil filled via oil fill port 23 (forming a closed chamber).

[0026] The pressure multiplier arrangement disclosed is thereforeoperative, upon supply of actuating pressure to the housing 17 via inlet18, to provide a low pressure and high volume output to perform theinitial loading of the tool 14, and a high pressure, low volume outputto provide a multiplied hydraulic force applied to the actuator element(outer hydraulic setting sleeve 19) to set the plug or other componentin a required position in the wellbore.

[0027] The low pressure piston 20 and the high pressure piston 21 areconnected together by a detachable connection, as mentioned above, andwhich yields under a predetermined load in order to allow the highpressure piston 21 to apply the multiplied hydraulic force to theactuator element.

[0028] A ratchet arrangement 26 is mounted in the housing 17, and it hasthe function of preventing return movement of the low pressure piston 20after yielding of the connection.

[0029] As shown in FIG. 1b, the low pressure piston 20 is an annularpiston, and the high pressure piston 21 is a rod like piston.

[0030] The disclosed embodiment of hydraulically operated setting toolaccording to the invention can therefore be used to set a plug or othercomponent in a wellbore, and has the advantage of providing the benefitsof using a non-pyrotechnic setting tool i.e. avoiding the dangers andinconveniences of using an explosive tool, but having the performance,output and short length associated with use of explosive type settingtools. The hydraulic operation of the tool, upon actuation by supply ofinput actuating pressure, utilizes two hydraulic chambers, in which onechamber will always be at atmospheric pressure, whereas the other onewill be at atmospheric pressure until the tool is operated, and willthen be exposed to high pressure from both the low pressure piston 20and the high pressure piston 21. The plug (not shown) is attached by theshear stud 16, and the two assemblies, housing 17 and adapter 15, arethreaded together. The outer “setting sleeve” (19) butts on the outsideof the plug, and effectively pushes the plug down, while the shear stud16 remains anchored to the internal components of the plug, during“setting” of the plug.

[0031] Once the plug is fully set, the shear stud 16 will separate(under load of 30,000 lbs or more), and this detaches the plug from thesetting tool.

[0032] The design of the plug adaptor 15 is not critical, but will bedesigned according to the particular proprietary type of plug which isutilised.

[0033] To conclude, the hydrostatically operated setting tool disclosedherein addresses an industry requirement for a non-pyrotechnic settingdevice for downhole use. The setting tool converts the hydrostaticpressure at the tool into an axial force. The short overall length ofthe tool can be achieved by incorporating a high volume low-pressurepiston and a low volume high-pressure piston into the setting tool. Thishydraulically operated pressure multiplier arrangement, combined with aunique regulating device within the tool, allows the hydrostatic wellpressure to be boosted within the tool, providing a force of about29,000 lbs for each 1,000 psi well pressure. The setting tool has beendesigned to run on slickline, and also electric line, but can also beadapted for coil tubing and pipe applications. The setting tool can bequickly converted from slickline to electric line deployment on a rigsite, by replacing two components at the top of the tool.

[0034] When run on slickline, a timer is used, which features anexternal switch allowing the timer to be started just before the toolstring is picked up. A timer disconnect feature is also provided, in theevent that the tool string hangs up R.I.H. This feature can be enabledor disabled as required.

[0035] In the event of insufficient hydrostatic pressure being availablee.g. during low level drilling, a pressure module may be run on top ofthe setting tool to provide sufficient input pressure. This would onlybe required if it were not possible to apply pressure from surface.

[0036] The hydrostatic setting tool is ideally suited to tree change outoperations, where pressure may be applied against a deep-set plug.

[0037] The setting tool provides a highly cost effective alternative toexisting use of pyrotechnic setting tools. In the case of slicklineoperation, the slickline timer is powered by two AA cell lithiumbatteries, which do not require dangerous goods certification fortransportation. This feature, combined with the short overall length ofthe tool, makes it ideal for transportation by helicopter.

[0038] The illustrated embodiment provides a detachable connectionbetween the low pressure piston and the high pressure piston, and takingthe form of a shear pin. However, it is within the scope of theinvention to provide a hydraulic connection between the low pressurepiston and the high pressure piston, and which couples these pistonstogether, and is adjustable from piston to piston to provide requiredoutput.

[0039] If there is insufficient pressure available in the wellbore, areservoir may be provided to increase the activating pressure suppliedto the tool. The reservoir may take the form of a nitrogen gas pressurebottle or accumulator, screwed onto the top of the tool.

1. A hydraulically operated setting tool for use in setting a plug orother component in a wellbore, said tool being responsive to a supply ofinput actuating pressure to actuate the tool, and comprising: anelongate housing which is movable lengthwise during lowering and raisingmovement of the tool in the wellbore, said housing having an inlet toreceive the supply of actuating pressure; an actuator element axiallydisplaceable relative to the housing and engageable with said componentto set and release said component with respect to the wellbore; and apressure multiplier arrangement in the housing and operative, uponsupply of actuating pressure to the housing, to provide a low pressurehigh volume output to perform the initial loading of the tool, and ahigh pressure, low volume output to provide a multiplied hydraulic forceapplied to the actuator element to set said component in a requiredposition in the wellbore.
 2. A setting tool according to claim 1, inwhich the pressure multiplier arrangement comprises a low pressurepiston and a high pressure piston connected together by a detachableconnection, such connection yielding under a predetermined load in orderto allow the high pressure piston to apply the multiplied hydraulicforce to the actuator element.
 3. A setting tool according to claim 1,in which the pressure multiplier arrangement comprises a low pressurepiston and a high pressure piston connected together by a hydraulicconnection, which is operative to couple the high pressure piston to thelow pressure piston, and vice versa, to provide required output.
 4. Asetting tool according to claim 2 or 3, including a ratchet arrangementin the housing which is operative to prevent return movement of the lowpressure piston after yielding of said connection.
 5. A setting toolaccording to any one of claims 2 to 4, in which the low pressure pistonis an annular piston, and the high pressure piston is a rod-like piston.6. A setting tool according to any one of the preceding claims, in whichthe housing has an inlet for receiving wellbore pressure to actuate thetool.
 7. A setting tool according to any one of claims 1 to 5, in whichthe housing is arranged to receive a supply of actuating pressure routedfrom the surface of the wellbore.
 8. A setting tool according to any oneof the preceding claims, in which a connector module is connected to anupper end of the housing, and is operative to raise and lower the tool.9. A setting tool according to claim 8, in which the connector module isone of: a) an adapter connectable to an electric wireline cable; b) amemory clock type device connectable to a slickline; or c) a hydraulicconnector for use at shallow drilling depth and connectable to a surfacesupply of actuating pressure.
 10. A setting tool according to any one ofthe preceding claims, including a reservoir of additional pressureprovided on the tool, and operative to apply additional actuatingpressure when necessary, in order to actuate the tool.
 11. A settingtool according to any one of the preceding claims, including a shearstud projecting downwardly from the housing and engageable with saidcomponent.
 12. A setting tool according to claim 9, in which the shearstud is provided on a plug adapter connected to a lower end of the toolhousing.
 13. A method of setting a plug or other component in awellbore, utilizing a tool according to any one of the preceding claims.